By Khaled Suleiman 

DAMASCUS  

Five Syrian civilians were killed in a regime airstrike near capital Damascus on Sunday, according to local sources.

Regime warplanes struck opposition-held residential areas in Douma city in Rif Dimashq province with cluster bombs, the sources told Anadolu Agency.

“Five civilians were killed and 18 others injured in the strikes,” the sources added anonymously due to security concerns.

The sources said the attack has left a vast trail of destruction in the city.

Syria has been locked in a vicious civil war since early 2011, when the Bashar al-Assad regime cracked down on pro-democracy protests -- which erupted as part of the "Arab Spring" uprisings -- with unexpected ferocity.

Since then, more than a quarter of a million people have been killed and more than 10 million displaced across the war-battered country, according to the UN.

The Syrian Center for Policy Research, however, put the death toll from the six-year conflict at more than 470,000 people.